A high ankle sprain is a sports medicine injury to the ligaments above the ankle that connect the two lower leg bones ( the tibia and the fibula) to each other.
These bones and ligaments comprise a “syndesmosis” – a joint in which bones are joined together by connective tissues such as ligaments and membranes, with only slight movement allowed.
As a result, high ankle sprains are sometimes referred to as syndesmotic injuries or syndesmotic ligament injuries.
This type of foot and ankle injury is far less common than the common ankle sprain (or low ankle sprain) which normally affects the ligaments on the outside of the ankle.
Anatomy Of A High Ankle Sprain
As mentioned above, a high ankle sprain is one that causes damage to the ligaments above the ankle joint instead of to those on its outside (as happens with a normal inversion ankle sprain).
These ligaments are responsible for joining the two lower leg bones (the tibia and the fibula) in what is known as a syndesmosis. The soft tissues in the syndesmosis actually include two ligaments and a membrane:
The anterior inferior tibiofibular ligament (or AITFL) runs in front of the shin and connects its two bones (tibia and fibula) together;
The posterior inferior tibiofibular ligament (or PITFL) also joins the tibia and fibula bones, but runs behind them instead of in front;
The third source of support for the two bones is the interosseous membrane that runs between the two bones and connects them along their length.
What’s the Cause Of A High Ankle Sprain?
High ankle sprains are usually the result of twisting or rotational forces being applied to the foot. In most cases, these forces cause external rotation of the foot (i.e. away from the body) with respect to the remainder of the leg. This type of force or impact usually happens in contact sports like hockey, for example.
The result of this twisting force is to cause damage first to the deltoid ligament on the inside of the ankle. However, the forces causing this damage are then transmitted up along the leg and through the syndesmosis ligaments listed above. The result of this damage to the syndesmosis ligaments will be pain just above the ankle at the point where the fibula and tibia meet.
Very high forces can continue up through the leg into the fibula itself, and can result in a fracture of the fibula well above the ankle This type of bone fracture is known as a Maisonneuve fracture..
The symptoms of a high ankle sprain normally depend on whether or not there is an associated fracture of the fibula:
If the patient suffers a fibula fracture, he or she typically won’t be able to bear weight on the injured foot.
If there is a high ankle sprain but no fracture, the patient will probably start to experience pain whenever performing activities that require foot flexion (i.e. moving the foot so that the toes point upward). This is a result of the stretching of the syndesmosis ligaments required when the foot is flexed. The most common activity that requires foot flexion would be climbing stairs so this is where the patient will most likely notice the pain.
Individuals experiencing these symptoms should seek medical advice at the earliest opportunity.
Diagnosing & Treating High Ankle Sprains
To diagnose a high ankle sprain, a doctor will likely conduct a physical examination of the injured lower leg and ankle.
A key goal will be determining whether the patient is experiencing pain at ankle level or above it. The patient may be asked to explain how the injury occurred.
The doctor will likely check for tenderness over the deltoid ligament on the inside of the ankle. That could be an indicator of the presence of a Maisonneuve injury as indicated above.
Palpation of the ankle (i.e. examination by touching) will probably be the preferred way to determine the location of the pain. Syndesmosis injuries will result in pain just above the ankle, whereas injuries to the lateral ligaments will cause pain at ankle level.
Two tests are normally critical in diagnosing a high ankle sprain:
The doctor may perform a “squeeze test” by squeezing the leg just below the knee. If the pain radiates down to the ankle, this would be a suggestion of a high ankle sprain;
The external rotation test involves having the patient bend the knee, keeping the ankle at a 90 degree angle in relation to the leg, and rotating the foot to the outside (away from the body). If the patient feels pain over the ankle, this is another indication of a high ankle sprain.
To confirm whether the high ankle sprain is accompanied by a bone fracture (ankle or fibula), doctors also need to conduct an imaging test such as an X ray scan. MRI or CT scans may also be used to assess the space between the tibia and the fibula and whether the syndesmotic ankle ligaments are managing to keep those two bones sufficiently close together.
In general, treating a high ankle sprain requires moving the tibia and fibula back into their correct positions relative to each other. They must then be kept in this position while healing proceeds.
Generally speaking, high ankle sprains require much longer to heal than do regular ankle sprains involving the lateral ligaments.
For patients without a fractured fibula, treatment will be simlar to that of a regular ankle sprain, and may include:
Resting the injured foot and ankle;
Icing them, or applying a cold compress at intervals of 20 minutes or so;
Elevating the leg above heart level to improve blood flow back to the heart;
Possibly wearing a walking boot to help keep the foot stable.
Physical therapy will be an important step in the treatment/recovery process. It will improve the strength of lateral ankle tendons (peroneal tendons) as well as help the patient recover ankle range of motion.
If the doctor detects the presence of a bone fracture, it is likely that surgery will be recommended to repair the injury. In general, the surgeon will restore the closeness of the tibia and fibula and hold them together with screws or suturing while healing proceeds.
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